Warhead projectile



Dec. 8, 1964 E. NOOKER WARHEAD PROJECTILE 5 Sheets-Sheet l Filed April28, 1961 BY WOW ATTORNEYS Dec. 8, 1964 E. NOOKER 3,160,099

- WARHEAD PROJECTILE Filed April 28, 1961 5 Sheets-Sheet 2 FIG. 3.

EUGENE L. NOOKER INVENTOR ATTORNEYS Dec. 8, 1964 E. 1.. NOOKER 3,150,099

7 WARHEAD PROJECTILE Filed April 28, 1961 s Sheets-Sheet 4 F' I G 6 a VI FIG. .7. a

ZONE 4 J ZLEi ZONE 5 ZONE I ZONE 2 omemm. sum

POSITION I E P 5 EUGENE L NOOKER INVENTOR BY QMCQ.

ATTORNEYS least three factors; the design of the hinge joint, the rodmotion during unfolding, and factors affecting the prop erties of therod materials. The rod motion will determine the severity of the hingejoint opening process, and the rod material properties in combinationwith the hinge joint design will determine to what degree the joint canopen before rod breakage occurs for the existing conditions of rodmotion. In particular, the sharpness of the rod bend and the rate atwhich stresses are applied to the weld regions will be critical factors.This invention is directed primarily to a hinge joint design capable offulfilling the operational requirements of continuous rod warheads,particularly those employing steel rods of rectangular cross-section.

A hinge joint made according to the invention is shown diagrammaticallyin FIGS. 5 and 6, wherein is seen an inner rod 6 and an outer rod 8. Therods 6 and 8 are connected by welding, the regions where such weldingoccurs being indicated by the cross-hatched areas. It should beunderstood that the weld representatives in FIGS. 5 and 6 are onlyschematic, and that in an actual hinge joint there are nodistinguishable boundary lines between the welded portions and theunwelded portions of the rods.

The hinge weld consists of two regions, a primary weld region, indicatedby the dimension P, and a secondary weld region, indicated by thedimension S. As is best shown in FIG. 6, which view is a cross-sectiontaken on line 6-6 of FIG. 5, the primary weld region P extends the fullwidth of the rods, whereas the secondary weld region S is generallytriangular in shape in the horizontal plane and has a progressivelydecreasing crosssectional area toward the central body of the rods. Theweld between the rods may be made by the resistance welding method.Prior to such a welding operation a shim, of a material that may be thesame as or dififerent from the material of the rods, is inserted betweenthe rods. The shim, in addition to other important functions not hereindiscussed, furnishes material to the weld regions so that the size ofthe rods is not reduced by the welding. process. The welding processemployed to make the weld is the subject matter of another invention,identified as patent application Serial Number 113,592, filed May 26,1961, and entitled Resistance Welding Process and is capable ofproducing a large number of individual welds having substantiallyidentical properties. Hence, in a continuous rod projectile the weldsemployed to connect each pair of rods will have substantially identicalcharacteristics.

The primary weld region P is a region where a complete fusion andthorough diffusion exists between the material of the two rods and ofthe shim placed therebetween. The primary region P must be as strong asis possible, as it must Withstand the major portion of the stressesacting upon the rods during unfolding.

The secondary weld region S is a region where a weld of less strengthexists than the weld of region P. The secondary weld adds strength tothe total hinge joint. Additionally, it functions in a unique manner tocontrol, to a degree, the radius about which the rod bends at the hingejoint (the bend radius), and to control the rate at which stress isapplied to the primary weld during the unfolding process. By controllingthe bend radius very sharp bends in the rods are avoided, and hence thepossibility of the rods failing by breaking through the region of thebend is greatly reduced. By controlling the rate at which the primaryweld is stress loaded, failures commonly associated with very abruptloading are avoided. The secondary weld obtains these results because ofits generally triangular shape and because it has less strength than theprimary weld, whereby it fails progressively as the projectile unfolds.

The manner in which the continuous rod projectile unfolds afterexplosion of its associated high explosive charge is shownschematically, in idealized form, in

FIGS. 8 and 9. In FIG. 8 the projectile is partially unfolded. As theinner and outer rods 6 and 8 separate, they bend about the hinge joint10. During such opening of the hinge joint, the secondary weld S willfail, or tear, progressively, the triangular configuration of the weldregion acting to control the rate at which the tearing progresses. Thisprogressive failure allows the bend radius of the rods to increaseslowly as the rods unfold, thereby avoiding very sharp bends.Additionally, the stresses associated with the rod unfolding process areapplied progressively to the primary weld region. In FIG. 9, theunfolding operation has continued, and it will progress until the innerand outer rods are substantially in axial alignment when the projectileis fully expanded. Further expansion of the projectile will then causeone or more of the hinge joints to fail, resulting in breakup of theprojectile.

A hinge joint is shown in perspective in FIG. 10 after the projectilehas reached its maximum expansion. The secondary weld S is shown at 14-in its failed condition, the primary weld P still being substantiallyintact and holding the rods together.

It is thus seen that a hinge joint consisting of a primary weld regionand a secondary weld region, constructed as herein described, willprovide a connection between the rods of a continuous rod projectilethat will allow for controlled bending of the rods, and that willcontrol the rate of application of stresses to the primary weld.

The particular dimensions and the materials employed in a projectile aredetermined by a number of factors, such as the overall warhead design,its geometry, the high explosive employed, etc. In a typical warhead,the dimensions of the rods 6 and 8 may be, by way of example, one-fourthinch on a side, and about eighteen inches in length, and the material ofthe rods may be S.A.E. 1008 steel. In such a projectile, the primaryweld region P would be about three-eighths inch in length, and thesecondary weld region S would be about five-eighths inch in length.

As has been indicated, the physical properties of the primary weldregion and the secondary weld region are very important to thesuccessful operation of the hinge joint. In particular, there must be acomplete fusion and a thorough diffusion of the material in the primaryweld region, and the properties of both the primary and the secondaryweld regions must meet at least a minimum standard in each of the hingejoints employed in the projectile. If one hinge joint were to be belowsuch a minimum standard, it would provide a point at which a fracturecould occur during the early stages of unfolding, hence destroying thenecessary continuity of the projectile. The geometry of the secondaryweld must be so designed as to properly control the bend radius, suchdesign being dependent upon the dimensions and materials of the rodsemployed, as well as other factors.

An example of the metallurgical structure desirable in a typical hingejoint is shown schematically in FIG. 7, said view representing an axialcross-section taken through the rod centers. For purposes of theexample, it is assumed that the rods measure one-fourth inch on a side,are of S.A.E. 1008 steel, have a Rockwell B scale hardness of about 75,and that they are welded by the resistance method with the use of ashim. The shim is assumed to be of S.A.E. 1008 steel having a Rockwell Bhardness of -85 and is elliptical in cross-section, the major and minoraxis of the ellipse measuring about 0.142 inch and 0.055 inch,respectively.

For such materials, the metallurgical structure of the Weld region,after welding, but before the welded rods have been annealed, should besubstantially as follows:

Zone 1: Completely recrystallized ferrite. Grain size 3-4. Zone 2:Completely recrystallized ferrite. Grain size 46.' Zone 3: Completelyrecrystallized ferrite. Grain size 5-6. Zone 4: Completelyrecrystallized ferrite. Grain size 5-6. Zone 5: Partially recrystallizedferrite. Grain size 67.

After annealing of the welded rods, the structure of the Weld regionshould be:-

ZOne 1: Completely recrystallized ferrite. Grain size 3-5. Zone 2:Completely recrystallized ferrite. Grain size 3-4. Zone 3: Completelyrecrystallized ferrite. Grain size 34. Zone 4: Completely recrystallizedferrite. Grain size 3-4. Zone 5: Completely recrystallized territe.Grain size 3-4.

The hardness of the hinge Weld should be substantially uniformthroughout, and complete fusion exists in the primary weld region.

It is to be understood that this invention is not limited to rods of anyparticular dimensions, nor of any particular material. Hingejoints-constructed according to the invention are useable in projectilesof any of a number of possible dimensions and materials, and theyfunction in all cases to maintain the continuity of the expandingcontinuous rod projectile.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically descirbed.

What is claimed is:- e

1. In a warhead projectile including a plurality of rods, said rodsbeing arranged in layers, corresponding end portions of the rods of onelayer being juxtaposed with respectto corresponding end portions of therods of another layer, a hinge weld for rigidly connecting saidjuxtaposed end portions, including a primary weld region at the endportions of the rods wherein substantially complete fusion existsbetween the material of the juxtaposed cross-sectional area from saidprimary weld region toward the central portions of said rods.

4. A continuous rod warhead projectile including a plurality of rods,said rods being arranged in layers, corresponding end portions of therods of one layer being juxtaposed with respect to corresponding endportions of the rods of another layer, a hinge weld rigidly connectingthe juxtaposed end portions of the rods, said hinge weld including aprimary weld region of relatively great strength at the end portions ofthe rods and a secondary weld region of comparatively less strength thansaid primary weld region, said secondary weld region being positionedlongitudinally inwardly of said primary weld region and away from theouter ends of the rods, said hinge weld being confined entirely betweenthe end portions of the rods.

rod portions, and a secondary weld region of relatively lessstrengththan said primary weld region, said secondary Y weld regionbeing positioned longitudinally inwardly of tionally said primary weldregion and said secondary weld region are coterminious.

3. A hinge weld as claimed in claim 2, wherein additionally saidsecondary weld progressively decreases in 5. A continuous rod warheadprojectile including a plurality of rods, said rods being arranged inlayers, corresponding end portions of the rods of one layer beingjuxtaposed with respect to corresponding end portions of the rods ofanother layer, a hinge weld rigidly connecting the juxtaposed endportions of the rods, said hinge weld including a primary Weld region atthe end portions of the rods wherein substantially complete fusion andthorough difiusion exists between the material of the juxtaposed rodportions, and a secondary weld region of relatively less strength thansaid primary weld region, said secondary weld region being contiguous tosaid primary weld region and being spaced longitudinally inwardly fromthe outer ends of the rods, said hinge weld being confined entirelybetween the end portions of the rods.

6. A continuous rod warhead projectile as claimed in claim 5, whereinthe cross-sectional area of said secondary weld region progressivelydecreases from said primary weld region toward the central portions ofsaid rods.

References Cited in the file of this patent UNITED STATES PATENTS1,211,001 Steinmetz Jan. 2, 1917 1,247,331 Robinson Nov. 20, 19172,452,659 Huldt Nov. 2, 1948 2,662,277 Stone Dec. 15, 1953 2,972,950Wclanetz Feb. 28, 1961

1. IN A WARHEAD PROJECTILE INCLUDING A PLURALITY OF RODS, SAID RODSBEING ARRANGED IN LAYERS, CORRESPONDING END PORTIONS OF THE RODS OF ONELAYER BEING JUXTAPOSED WITH RESPECT TO CORRESPONDING END PORTIONS OF THERODS OF ANOTHER LAYER, A HINGE WELD FOR RIGIDLY CONNECTING SAIDJUXTAPOSED END PORTIONS, INCLUDING A PRIMARY WELD REGION AT THE ENDPORTIONS OF THE RODS WHEREIN SUBSTANTIALLY COMPLETE FUSION EXIST BETWEENTHE MATERIAL OF THE JUXTAPOSED ROD PORTIONS, AND A SECONDARY WELD REGIONOF RELATIVELY LESS STRENGTH THAN SAID PRIMARY WELD REGION, SAIDSECONDARY WELD REGION BEING POSITIONED LONGITUDINALLY INWARDLY OF SAIDPRIMARY WELD REGION AND AWAY FROM THE OUTER ENDS OF THE RODS, SAID HINGEWELD BEING CONFINED ENTIRELY BETWEEN THE END PORTIONS OF THE RODS.